Car threw a P0305 code (misfire detected on Cylinder #5) a couple weeks ago at around 41,500 miles. With a weather change I thought it might have been a random code (first code the car has thrown since new) so I reset it and moved on.

10 days later code came back, with reduced power (4500 redline) and rough running. Both instances were at relatively light load (38% on TPS on snapshot data) at highway speeds. A restart cured the reduced power but did not clear the SES. Took to dealer and #5 cyl. coil was found bulged, was replaced along with the spark plug, and now all is well. The dealer did what I would have done first, except I would have had to go through the extra step of moving the coil to see if the fault moved with the coil and they were able to confirm it was bad with their diags.